139 research outputs found
In vivo targeted molecular imaging for activated platelets by mri using USPIO-fucoidan in rat abdominal aortic aneuryms model
POSTER PRESENTATIONInternational audienc
Breakdown of the Z = 8 Shell Closure in Unbound O and its Mirror Symmetry
Expérience GANIL, SISSI, MUST2/E537International audienceAn excited state in the proton-rich unbound nucleus 12O was identified at 1.8(4) MeV via missing-mass spectroscopy with the 14Oðp; tÞ reaction at 51 AMeV. The spin-parity of the state was determined to be 0þ or 2þ by comparing the measured differential cross sections with distorted-wave calculations. The lowered location of the excited state in 12O indicates the breakdown of the major shell closure at Z ¼ 8 near the proton drip line. This demonstrates the persistence of mirror symmetry in the disappearance of the magic number 8 between 12O and its mirror partner 12Be
Low-lying Proton Intruder State in 13B
The neturon rich nucleus 13B was studied via the proton transfer reaction
4He(12Be,13B \gamma) at 50AMeV. The known 4.83-MeV excited state was strongly
populated and its spin and parity were assigned to 1/2+ by comparing the
angular differential cross section data with DWBA calculations. This low-lying
1/2+ state is interpreted as a proton intruder state and indicates a
deformation of the nucleus.Comment: 16 pages, 3 figure
First application of mass measurement with the Rare-RI Ring reveals the solar r-process abundance trend at A=122 and A=123
The Rare-RI Ring (R3) is a recently commissioned cyclotron-like storage ring
mass spectrometer dedicated to mass measurements of exotic nuclei far from
stability at Radioactive Isotope Beam Factory (RIBF) in RIKEN. The first
application of mass measurement using the R3 mass spectrometer at RIBF is
reported. Rare isotopes produced at RIBF, Sn, In, Cd,
Ag, Pd, were injected in R3. Masses of In, Cd,
and Pd were measured whereby the mass uncertainty of Pd was
improved. This is the first reported measurement with a new storage ring mass
spectrometery technique realized at a heavy-ion cyclotron and employing
individual injection of the pre-identified rare nuclei. The latter is essential
for the future mass measurements of the rarest isotopes produced at RIBF. The
impact of the new Pd result on the solar -process abundances in a
neutron star merger event is investigated by performing reaction network
calculations of 20 trajectories with varying electron fraction . It is
found that the neutron capture cross section on Pd increases by a
factor of 2.2 and -delayed neutron emission probability,
, of Rh increases by 14\%. The neutron capture cross
section on Pd decreases by a factor of 2.6 leading to pileup of
material at , thus reproducing the trend of the solar -process
abundances. The trend of the two-neutron separation energies (S)
was investigated for the Pd isotopic chain. The new mass measurement with
improved uncertainty excludes large changes of the S value at
. Such large increase of the S values before was
proposed as an alternative to the quenching of the shell gap to
reproduce -process abundances in the mass region of
A new study of the and shell gap for Ti and V by the first high-precision MRTOF mass measurements at BigRIPS-SLOWRI
The atomic masses of Sc, Ti, and V have been
determined using the high-precision multi-reflection time-of-flight technique.
The radioisotopes have been produced at RIKEN's RIBF facility and delivered to
the novel designed gas cell and multi-reflection system (ZD MRTOF), which has
been recently commissioned downstream of the ZeroDegree spectrometer following
the BigRIPS separator. For Ti and V the mass uncertainties
have been reduced down to the order of , shedding new light
on the shell effect in Ti and V isotopes by the first high-precision
mass measurements of the critical species Ti and V. With the new
precision achieved, we reveal the non-existence of the empirical
two-neutron shell gaps for Ti and V, and the enhanced energy gap above the
occupied orbit is identified as a feature unique to Ca. We
perform new Monte Carlo shell model calculations including the
and orbits and compare the results with conventional shell model
calculations, which exclude the and the orbits. The
comparison indicates that the shell gap reduction in Ti is related to a partial
occupation of the higher orbitals for the outer two valence neutrons at
Isotope production in proton-, deuteron-, and carbon-induced reactions on Nb 93 at 113 MeV/nucleon
Isotope-production cross sections for p-, d-, and C-induced spallation reactions on Nb93 at 113 MeV/nucleon were measured using the inverse-kinematics method employing secondary targets of CH2, CD2, and C. The measured cross sections for Mo90, Nb90, Y86,88 produced by p-induced reactions were found to be consistent with those measured by the conventional activation method. We performed benchmark tests of the reaction models INCL-4.6, JQMD, and JQMD-2.0 implemented in the Particle and Heavy Ion Transport code System (PHITS) and of the nuclear data libraries JENDL-4.0/HE, TENDL-2017, and ENDF/B-VIII.0. The model calculations also showed generally good agreement with the measured isotope-production cross sections for p-, d-, and C-induced reactions. It also turns out that, among the three nuclear data libraries, JENDL-4.0/HE provides the best agreement with the measured data for the p-induced reactions. We compared the present Nb93 data with the Zr93 data, that were measured previously by the same inverse kinematics method (Kawase et al., Prog. Theor. Exp. Phys. 2017, 093D03 (2017)2050-391110.1093/ptep/ptx110), with particular attention to the effect of neutron-shell closure on isotope production in p- and d-induced spallation reactions. The isotopic distributions of the measured production cross sections in the Zr93 data showed noticeable jumps at neutron number N=50 in the isotopic chains of ΔZ=0 and -1, whereas no such jump appeared in isotopic chain of ΔZ=0 in the Nb93 data. From INCL-4.6 + GEM calculations, we found that the jump formed in the evaporation process is smeared out by the intranuclear cascade component in Nb91 produced by the Nb93(p,p2n) and (d,d2n) reactions on Nb93. Moreover, for Nb93, the distribution of the element-production cross sections as a function of the change in proton number ΔZ is shifted to smaller ΔZ than for Zr93, because the excited Nb prefragments generated by the cascade process are more likely to emit protons than the excited Zr prefragments, due to the smaller proton-separation energies of the Nb isotopes
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